JP6666639B2 - Molding machine and method of controlling molding machine - Google Patents

Description

The present invention relates to a molding machine in which a movable plate on which a movable mold is attached is moved by a mold opening / closing mechanism with respect to a fixed plate on which a fixed mold is attached, and press-clamping is performed by a pressure-clamp mechanism, and a control method therefor.

Conventionally, there is known a molding machine described in Patent Document 1 as a molding machine in which a movable plate on which a movable mold is mounted is moved by a mold opening / closing mechanism with respect to a fixed plate on which a fixed mold is mounted, and is pressed by a pressing mechanism. Have been. In the paragraph number (0014) of Patent Document 1, it is preferable to use a mechanical drive mechanism driven by a servomotor for a mold opening / closing mechanism for shortening a molding cycle, improving accuracy, and regenerating electric power as described later. It is described that a hydraulic cylinder may be used for the purpose of reducing equipment cost.

In FIG. 1 of Patent Document 1, two mold opening / closing mechanisms are provided in a mold clamping device including a fixed plate and a movable plate. An example is described in which the ball screw of each mold opening / closing mechanism is rotationally driven by one servomotor. However, in a relatively large molding machine in which a mold opening / closing mechanism and a pressing mechanism are separately provided, a large servomotor is required when the ball screw is driven to rotate by one servomotor. However, large-sized servo motors are few and expensive, and in some cases, there is no motor that matches the required capacity or a custom-ordered product is required. Further, when a small servomotor is used, it is necessary to increase the reduction ratio, so that there is a problem that a sufficient mold opening / closing speed cannot be obtained.

Further, a technique disclosed in Patent Document 2 is known in which a single ball screw is driven by two servomotors to open and close a mold and perform pressure clamping. However, in Patent Literature 2, the servomotor 10 is the only electric motor used to drive the mold opening / closing mechanism, and the movable platen is moved only by the servomotor 10. After the mold closing operation, the induction motor 18 is operated to tighten the mold.

Further, as a technique similar to Patent Document 2, a technique of Patent Document 3 is also known. In Patent Document 3, during normal mold opening and closing, the electric servomotor 58 is driven to rotate to rotate the ball screw to move the movable platen. It is described that the electric motor 38 is rotated after the mold is closed to press the movable platen against the fixed platen. Further, Patent Document 3, page 4, column 8 (right column) also describes that the electric servomotor 38 and the electric servomotor 58 are used in combination to further increase the mold opening / closing speed. However, in the method of Patent Document 3, it is very difficult to perform control to sufficiently exert the capabilities of both servomotors because the pitches of the ball screws rotated by the electric servomotor 38 and the electric servomotor 58 are different. There is. Further, the ball screw used in Patent Document 3 is a special one having a different pitch, and there is a problem that the cost of the device is increased.

JP-A-2015-77725 (0014, FIG. 1) Japanese Patent Publication No. 5-56249 (Claim 1, page 3, column 6 to page 4, column 7, FIG. 1) Japanese Patent Publication No. Hei 4-33255 (Claim 1, page 4, column 8, column 1)

The techniques disclosed in Patent Documents 2 and 3 move one ball screw by two electric motors. However, in a molding machine in which a mold opening / closing mechanism and a pressing mechanism are provided independently, It has not been able to adequately cope with problems such as reduction of device cost of the opening / closing mechanism or securing of mold opening / closing speed.

Therefore, according to the present invention, in a molding machine in which a movable plate on which a movable mold is mounted is moved by a mold opening / closing mechanism with respect to a fixed plate on which a fixed mold is mounted, and press-clamping is performed by a press-clamping mechanism, the apparatus cost is reduced or the die It is an object of the present invention to provide a molding machine capable of securing an opening / closing speed and a method of controlling the molding machine.

A molding machine according to claim 1 of the present invention, in which a movable plate on which a movable mold is mounted is moved by a mold opening / closing mechanism with respect to a fixed plate on which a fixed mold is mounted, and press-clamping is performed by a press-clamp mechanism. Wherein the mold opening and closing mechanism comprises: at least two ball screws; at least two electric motors each driving one of the ball screws; a ball screw nut into which each of the ball screws is inserted; Is provided.

According to a second aspect of the present invention, in the molding machine according to the first aspect, the two leads respectively drive a ball screw having an equal pitch, two driven pulleys fixed to the ball screw, and the ball screw. Two electric motors, a drive pulley fixed to a drive shaft of the electric motor, and a driven pulley of one of the two driven pulleys and a drive pulley of one of the two electric motors. One of the two driven belts, the other of the two driven pulleys and the other of the two motors, and the other of the two motors, the other of which is wound around the drive pulley of the other motor, and the two ball screws And a ball screw nut through which each is inserted.

According to a third aspect of the present invention, in the molding machine according to the first or second aspect, four tie bars are inserted through the movable plate, and are lower than the circumferential upper end surfaces of the two lower tie bars. A ball screw nut is fixed to each side.

According to a control method of a molding machine according to a fourth aspect of the present invention, a movable plate on which a movable mold is attached is moved by a mold opening / closing mechanism with respect to a fixed plate on which a fixed mold is attached, and pressure is clamped by a pressure clamping mechanism. In the method of controlling a molding machine to be performed, the mold opening / closing mechanism includes at least two ball screws, at least two servo motors driving one ball screw among the ball screws, and each ball screw being inserted. Wherein the position of the movable platen is detected by an encoder of one of the servomotors.

The molding machine of the present invention is a molding machine in which a movable plate on which a movable mold is attached is moved by a mold opening / closing mechanism with respect to a fixed plate on which a fixed mold is attached, and press-clamping is performed by a pressure clamping mechanism. Is provided with at least two ball screws, at least two electric motors for driving one ball screw of each ball screw , and a ball screw nut into which each ball screw is inserted. Further, it is possible to reduce the cost of the apparatus or to secure the mold opening / closing speed.

It is a front view of the injection molding machine of this embodiment. It is a top view of the injection molding machine of this embodiment. It is a side view of the injection molding machine of this embodiment. It is a side view of the injection molding machine of another embodiment. It is a front view of the injection molding machine of yet another embodiment. It is a front view of the injection molding machine of another embodiment from FIG.

FIG. 1 is a front view of an injection molding machine 11, which is one type of a molding machine of the present invention, in which a cover and a safety door are omitted. The injection molding machine 11 of the present embodiment will be described with reference to FIGS. 1 and 2. The hybrid injection molding machine 11 using both a hydraulic mechanism and an electric drive mechanism includes an injection device 12 on one side (the right side in FIG. 1). And a mold clamping device 13 on the other side (the left side in FIG. 1).

First, the injection device 12 will be described. As the injection device 12, a known electric injection device is used, and a screw forward / backward movement mechanism and a screw rotation mechanism (not shown) are driven by an electric motor. In the injection device 12, a nozzle 15 is provided on a tip side of a heating cylinder 14 provided with a heater (not shown). A material supply device 16 is provided on a housing plate (not shown) near the rear portion of the heating cylinder 14. A screw (not shown) is provided in the inner hole of the heating cylinder 14. The screw can be rotated by the screw rotating mechanism and can be moved forward and backward by the screw moving mechanism. Note that the injection device 12 may use a hydraulic mechanism.

Next, the mold clamping device 13 will be described. The mold clamping device 13 moves the movable platen 20 on which the movable mold 19 is mounted with respect to the fixed plate 18 on which the fixed mold 17 is mounted by the mold opening / closing mechanism 21 and performs pressure clamping. Pressing is performed by the mechanism 22. A molding machine in which the mold opening / closing mechanism 21 and the pressing mechanism 22 are provided independently as in the injection molding machine 11 is relatively large. Although a relatively large molding machine is not limited to this, for example, the mold clamping force (compression force) is 10,000 kN or more, and the upper limit includes all practically used ones. For example, the mold clamping force is 70,000 kN or less.

On the bed 23, a fixed plate 18 is fixedly erected. The fixed board 18 has a plurality of ribs (not shown) on the rear surface of the mold mounting surface 24 to which the fixed mold 17 is mounted, and the entire board is not a solid member. A concave portion 26 is formed in the center of the fixed plate 18 on the side of the back surface 25, through which the heating cylinder 14 and the nozzle 15 of the injection device 12 are inserted. The nozzle 15 of the injection device 12 can be brought into contact with the fixed mold 17 via the recess 26 and a locating ring (not shown). In the present embodiment, the molds 17 and 19 are clamped by a mold clamping cylinder 27 which is a pressure clamping mechanism 22 using a pressure medium (hydraulic oil). The mold clamping cylinders 27 are respectively provided near the four corners of the fixed plate 18, and the rod of the mold clamping cylinder 27 constitutes a tie bar 28. The tie bar 28 is formed with a groove 28a for engaging a half nut in the circumferential direction.

The movable platen 20 is formed of a plurality of ribs (not shown) on the back side of the mold mounting surface 29 to which the movable mold 19 is mounted, and is not a solid member as a whole. The thickness of the main body of the movable platen 20 (the thickness from the mold mounting surface 29 to the rear surface 30) is greater than the thickness of the main body of the fixed plate 18 (the thickness from the die mounting surface 24 to the rear surface 25). ing. The tie bars 28 are slidably inserted into the inner holes of the cylindrical bush 31 near the four corners of the movable platen 20, respectively. Half nuts 32 are provided on the back surface 30 of the movable platen 20 around the mounting positions of the bushes 31 so as to engage with the grooves 28a. Further, the movable plate 20 is also provided with an ejector mechanism and the like (not shown). A ball screw nut 33 of the mold opening / closing mechanism 21, which will be described later, is fixed to a position below the circumferential upper end surface 28b of the tie bar 28 below the movable platen 20.

At least two guide rails 34 (or guide plates) are provided on the upper surface of the bed 23 in the directions of one side and the other side in FIGS. The movable platen 20 is movable in the mold opening / closing direction along the guide rail 34. The movable board 20 is provided with legs 35 on the bed side (ground contact side). In the present embodiment, the horizontal length L of the leg 35 including the board of the movable board main body is equal to the height H (excluding the height of the bed 23) of the board including the leg 35 of the movable board 20. It has a length of 1/2 or more. The reason for providing the long leg 35 in this manner is as follows. That is, if the ball screw nut 33 is attached to a position lower than the circumferential upper end surface 28b of the lower two tie bars 28 of the movable platen 20, the movable platen 20 tends to become unstable when the movable platen moves. Therefore, the leg portion 35 is provided to be long for the measure. Also, since the movable mold 19, which is a heavy object, is attached to the mold mounting surface 29 of the movable board 20, the legs 35 are directed forward (toward the fixed board) to prevent the movable board 20 from falling forward. The extension is provided. A moving unit mechanism (not shown) provided on the bottom surface of the leg 35 of the movable platen 20 may use a linear moving member such as a linear guide (registered trademark), and is provided with a rotating moving body such as wheels or rollers. May be. Further, at least one of the bottom surface of the leg portion 35 and the guide plate may be provided with a sliding body having low friction characteristics such as a turkey plate, so that the movable platen 20 slides.

In the present embodiment, the end of the tie bar 28 is inserted into a tie bar holder 36 erected on the upper surface of the bed 23 on the other side of the movable platen 20. The relationship between the tie bar holder 36 and the tie bar 28 is such that the circumferential surface of the tie bar 28 is slidably inserted into the tie bar holder 36. The tie bar holder 36 is a member that does not receive the mold clamping force, and is a thin plate body as compared with the fixed plate 18 and the like. As shown in FIG. 3, the tie bar holder 36 has a frame shape with a space in the center, and the tie bars 28 are inserted near four corners of the tie bar holder 36. In the present embodiment, the lower portion of the portion where the lower tie bar 28 is inserted in the tie bar holder 36 is a holding portion 37 that holds a part of the mold opening / closing mechanism 21. The tie bar holder 36 may hold only the lower tie bar 28. Further, the tie bar holder 36 itself is not an essential member, and thus may not be arranged.

Next, the mold opening / closing mechanism 21 of the mold clamping device 13 will be described. In the present invention, the mold opening / closing mechanism 21 has a mechanical structure using an electric motor and a screw feed mechanism. The two mold opening / closing mechanisms 21 are both located below the movable platen 20 and are arranged on the bed 23 closer to the operation side and closer to the non-operation side. The mold opening / closing mechanism 21 closer to the operation side will be described. A bearing 39 is mounted on the holding portion 37 of the tie bar holder 36, and a ball screw 38 is inserted through the bearing so as to be rotatable and capable of receiving an axial force. ing. A bearing 41 is also mounted on a bracket 40 mounted on the upper surface of the bed 23 at an intermediate position between the fixed plate 18 and the movable plate 20 on the operation side. One end of the ball screw 38 is rotatably inserted into the bearing 41. Therefore, the ball screw 38 is held by the bearings 39 and 41 at both ends in parallel with the mold opening and closing direction. The ball screw 38 used in the present embodiment is a general one in which leads in an effective lead length portion are provided at an equal pitch.

As shown in FIG. 3, one driven pulley 42 and the other driven pulley 42 are provided in a portion other than the effective lead length portion on the other side (left side in FIG. 1) of the portion of the ball screw 38 which is held by the bearing 39. Two driven pulleys 43 are fixed slightly separated in the axial direction. At one and other positions on both sides of a portion of the holding portion 37 of the tie holder 36 to which the bearing 39 is attached, one servo motor 44 and the other servo motor 45, which are electric motors, have their drive shafts directed to the other side, respectively. Is fixed. Drive pulleys 46 and 47 are attached to the drive shafts of the servo motors 44 and 45, respectively. A timing belt 48 (belt) is stretched between the one driven pulley 42 and the drive pulley 46 of one servomotor 44 (electric motor). A timing belt 49 (belt) is stretched between the other driven pulley 43 and the driving pulley 47 of the other servomotor 45 (electric motor).

In this embodiment, the distance between the ball screw 38 and one servomotor 44 and the distance between the ball screw 38 and the other servomotor 45 are provided at equal intervals. However, the distance between the ball screw 38 and one of the servomotors 44 and the distance between the ball screw 38 and the other servomotor 45 may be different depending on the problem such as the space of the apparatus. In that case, naturally, the timing belts 48 and 49 also have different lengths according to the difference in the distance. Further, in the present embodiment, one servo motor 44 and the other servo motor 45 are servo motors having the same specifications. However, this does not exclude the case where one ball screw is rotationally driven by a servo motor having a different specification. Further, in each of the above combinations, the number of servomotors for driving one ball screw may be at least two, and may be three or four. Further, the servomotors 44 and 45 and the ball screw 38 may be mounted on a bracket of a mold opening / closing mechanism holding part on another bed 23 other than the holding part 37 of the tie bar holder 36. In that case, both the mold opening and closing mechanisms on the operation side and the non-operation side may be mounted on one bracket or may be mounted on separate brackets.

Since the mold opening / closing mechanism 21 on the non-operation side has the same structure as that of the mold opening / closing mechanism 21 on the operation side, different numbers are omitted and explanations thereof are omitted. 47 and the driven pulleys 42 and 43 of one ball screw 38 are connected, and one ball screw 38 is rotationally driven by two servo motors 44 and 45. As described above, in the method in which the two mold opening / closing mechanisms 21 and 21 are provided on the bed 23, the ball screws 38 and 38 can be arranged in a two-sided structure, so that the end-side swing when the ball screw rotates can be eliminated. Further, there is an advantage that wiring to the fixedly mounted servo motors 44 and 45 and lubrication to the ball screw 38 can be easily performed from inside the bed 23. Further, by providing the mold opening / closing mechanisms 21 and 21 below the movable platen 20, when the pipes are mounted on the dies 17 and 19 and the dies 17 and 19 to be replaced are mounted on the fixed platen 18 and the movable platen 20 from the horizontal direction. And the molding work of the worker becomes easy. When moving the movable platen 20, the upper portion tends to become unstable particularly, as described above, the thickness of the movable platen 20 is increased and the leg 35 is extended forward, and the tie bar insertion portion of the movable platen 20 is provided. The problem is solved by providing a bush 31 in which the peripheral surface of the tie bar 28 and the inner hole surface slide. The ball screw nut 33 of the mold opening / closing mechanism 21 may be attached near the tie bar 28 on the lower side of the movable platen 20. In that case, the width of the injection molding machine 11 is often required to be large, but in many cases, the height of the injection molding machine 11 can be suppressed.

Next, the control system of the present embodiment will be briefly described with reference to FIG. 2. The servo motor 44 of the operation side mold opening / closing mechanism 21 is connected to the servo amplifier 50, and the servo motor 45 is connected to the servo amplifier 51. The servo motor 44 and the servo motor 45 of the mold opening / closing mechanism 21 on the non-operation side are also connected to the servo amplifier 50 and the servo amplifier 51, respectively. Each of the servo amplifiers 50, 50, 51, 51 is connected to a higher-level control device 52. Then, the detected value of the encoder 44a of any one of the four servo motors 44, 44, 45, 45 is used for control as the position of the movable platen 20 and displayed on the display device 53. Therefore, the one servomotor 44 is closed-loop controlled as a master motor based on a command value from the control device 52, and the other three servomotors are slave motor positions (rotational angles detected by an encoder) as slave motors. ) Is performed. Note that the position control of the servo motors 44, 44, 45, 45 may be a method of controlling each motor independently with respect to the command position, and is not limited to the above. Further, a sensor using a position sensor such as a linear scale between the fixed plate 18 or the bed 23 and the movable plate 20 and using sensors other than the encoders of the servo motors 44 and 45 for control is not excluded.

Next, operation of the injection molding machine 11 and molding by the injection molding machine 11 will be described. FIG. 1 shows a state in which the movable platen 20 is stopped at the mold opening completion position, and the mold closing step is started from the state of FIG. In the mold closing process, four servomotors 44 and 45 (the reference numerals in the following description are assigned to only one mold opening / closing mechanism 21) are fully driven, and the respective ball screws 38 are connected to the timing belts 48 and 49. Is driven through. At this time, the servomotors 44, 45, and 45 are controlled to follow up as described above, so that the driving torque is transmitted to the ball screws 38, 38 without a large loss. When the movable platen 20 is rapidly accelerated and then moved at high speed, and the position of the movable platen 20 read by the encoder 44a of the servomotor 44 reaches a predetermined position, the four servomotors 44 are shifted to low-speed drive control, 20 is moved at low speed. Thereafter, the movable mold 19 is brought into contact with the fixed mold 17 through a control step of the mold protection section to form a cavity.

The half nut 32 is actuated at the same time as or slightly before the mold contact, and the teeth of the half nut 32 are engaged with the grooves 28 a of the tie bar 28. After that, the mold clamping cylinder 27 of the clamping mechanism 22 is operated to pull the tie bar 28 to clamp the mold composed of the fixed mold 17 and the movable mold 19. The servo motors 44 and 45 of the mold opening / closing mechanism 21 are made servo-free simultaneously with the mold contact or when the mold clamping force reaches a certain value. Then, when the mold clamping force is reached by the action of the set clamping mechanism 22, the screw forward / reverse mechanism of the injection device 12 is operated forward and the molten resin in the heating cylinder 14 is injected into the cavity in the mold via the nozzle 15. I do.

In the cooling step after the injection, the injection resin performs a next measuring step for molding in parallel with the cooling and solidification of the molten resin in the cavity. When a predetermined time has elapsed from the time of injection (completion of pressure holding as an example), the cooling step ends. Then, after the pressure in the oil chamber for mold clamping of the mold clamping cylinder 27 is released, the strong mold opening step is performed. The strong mold opening process is generally performed using a mold clamping cylinder 27, and the movable mold 19 is separated from the fixed mold 17 at a predetermined interval and the mold is opened. At this time, the servo motors 44 and 45 of the mold opening / closing mechanism 21 may be driven simultaneously or may remain servo-free. Further, depending on the structure of the molding machine, the powerful mold opening process may be performed by the servo motors 44 and 45 of the mold opening / closing mechanism 21. At this time, the molded product is generally held by the movable mold 19 and released. When the strong mold opening process is completed, the pressure in the oil chamber for opening the strong mold of the mold clamping cylinder 27 is released, and then the half nut 32 is detached from the engagement groove 28a of the tie bar 28.

In the next mold opening step (high-speed mold opening step), the four servomotors 44 and 45 are fully driven, and the movable platen 20 is rapidly accelerated and moved at a high speed as in the mold closing step. Be moved. Then, when the position of the movable platen 20 read by the encoder 44a of the servomotor 44 reaches the mold opening completion position, all the servomotors 44 and 45 stop driving. At this time, the control method of the servo motors 44 and 45 also conforms to the mold closing process. When the movable platen 20 and the movable mold 19 are positioned and stopped at the mold opening completion position, a molded product is taken out from the movable mold 19 by a robot (not shown), and one molding cycle is completed.

Next, a mold clamping device 62 of an injection molding machine 61 of another embodiment shown in FIG. 4 will be described. The mold clamping device 62 is the same as the example in FIG. 1 except for the arrangement of the mold opening / closing mechanisms 63 and 64. As for the mold opening / closing mechanisms 63 and 64, one mold opening / closing mechanism 63 is provided near the upper tie bar on the operation side of the fixed platen and the movable platen 60. The other mold opening and closing mechanism 64 is provided near the lower tie bar on the opposite side of the fixed platen and the movable platen 60. More specifically, a bracket 67 for attaching a motor and a ball screw is fixed to a side surface near a portion where the tie bar 66 on the operation side of the tie bar holder 65 is inserted. A bearing is fixed to a central portion of the bracket 67, and a ball screw 68 is rotatably inserted into the bearing. Servo motors 69 and 70 are fixed above and below the ball screw 68. A driven pulley 71 fixed to a ball screw 68 and a drive pulley 72 fixed to a drive shaft of one servomotor 69 are connected by one timing belt 74. Another driven pulley 71 fixed to the ball screw 68 and a driving pulley 73 fixed to the driving shaft of the other servomotor 70 are connected by the other timing belt 75. Although not shown, a ball screw nut is fixed to a bracket attached near the upper tie bar on the operation side of the movable platen 60, and a ball screw 68 is rotatably inserted into the ball screw nut. The ball screw 68 is held only by the ball screw nut, and the end of the ball screw 68 is not held by the bearing.

As for the other mold opening / closing mechanism 64, a bracket 76 is fixed to a side surface near a portion where the lower tie bar 66 on the opposite side to the operation side of the tie bar holder 65 is inserted, and two servo motors 69 and 70 are provided similarly to the operation side. , Drive pulleys 72, 73, timing belts 74, 75, and driven pulleys 71, 71, and the ball screw 68 is rotationally driven by two servo motors 69, 70. The ball screw 68 is rotatably inserted into a ball screw nut (not shown) provided below the movable platen 60 on the non-operation side. And the end of the ball screw 68 is not held like the operation side. However, the ball screw 68 of the other mold opening / closing mechanism 64 can also rotatably hold the end of the ball screw 68 on a bearing provided on a bracket on the bed 77. As a modification of the embodiment of FIG. 4, a mold opening / closing mechanism may be provided near the lower tie bar on the operation side and near the upper tie bar on the opposite side to the operation side. In the injection molding machine 61 of another embodiment shown in FIG. 4, the mold opening / closing mechanism is provided at a diagonal position with respect to the center axis of the movable board 60 and the fixed board. It often contributes to stable movement.

Next, an injection molding machine 81 of still another embodiment shown in FIG. 5 will be described focusing on differences from the embodiment shown in FIG. In the example shown in FIG. 5, the movable platen 83 of the mold clamping device 82 is a second movable platen on which a first movable platen 85 to which a movable mold 84 is mounted and a mold clamping cylinder 87 which is a pressing mechanism 86 are mounted. It consists of 88. The rear second movable platen 88 is directly mounted on the bed 89, and is movable on the bed 89. The second movable board 88 has a mounting table 90 extending downward at a lower portion, and the first movable board 85 is movably mounted on the mounting table 90 described above. The ram 91 of the mold clamping cylinder 87 provided on the second movable plate 88 is fixed to the back surface of the first movable plate 85. In the embodiment of FIG. 5, a mold opening / closing mechanism 92 similar to that of FIG. Both ends of the ball screw 93 of the mold opening / closing mechanism 92 are rotatably held by bearings provided on members such as a bracket and a tie bar holder on the bed 89. The mechanism using the two servomotors 94 is the same as in FIG. 1 and will not be described. Further, a ball screw nut 95 into which the ball screw 93 is inserted is fixed to the movable plate 83 (here, a side surface of the mounting table 90 of the second movable plate 88).

As a modification of the embodiment shown in FIG. 5, a first movable plate on the front side can be placed directly on a bed and can be moved, and the first movable platen has a mounting table fixed downward at the lower part. The second movable plate may be movably mounted on the mounting table described above. The ram of the mold clamping cylinder provided on the second movable plate is fixed to the back surface of the first movable plate. In this modification, a mold opening and closing mechanism similar to that of FIG. 1 is provided on a bed, and a ball screw nut is fixed to a movable plate (first movable plate).

Next, another embodiment different from FIG. 5 shown in FIG. 6 will be described. The molding machine shown in FIG. 6 is a vertical injection molding machine 101 in which four tie bars 103 are erected and fixed to a lower fixed plate (fixed plate) 102, and the tie bar 103 is fixed to an upper plate 104. A movable plate 105 is provided on the tie bar 103 so as to be movable in the vertical direction. One to four mold clamping cylinders 107 of a pressing mechanism 106 are fixed to the upper plate 104, and the ram 108 is fixed to the back surface of the movable plate 105. Two to four mold opening / closing mechanisms 109 are provided between the lower fixed board 102 or the bed and the movable board 105.

One of the mold opening / closing mechanisms 109 will be described. A bearing is attached to a side surface of the lower fixed platen 102 or a bracket 110 provided on a bed, and a base end side of a ball screw 111 is rotatably inserted. The ball screw 111 is a ball screw having leads of equal pitch, and has a shaft core mounted in a vertical direction. A plurality (two) of driven pulleys 112 are fixed to the base side (lower side) of the ball screw 111. At least two servo motors 113, 113 (electric motors) are fixed near both sides of the ball screw 111, and drive pulleys 114, 114 are fixed to their drive shafts, respectively. The drive pulleys 114, 114 of the servomotors 113, 113 and the driven pulleys 112, 112 of the ball screw 111 are connected by timing belts 115, 115 (belts).

On the other hand, a ball screw nut 117 is fixed to a bracket 116 provided on the side of the movable platen 105. The ball screw 111 is inserted through the ball screw nut 117. Therefore, the upper end side of the ball screw 111 is held only by the ball screw nut 117. It is not impossible to extend the length of the ball screw 111 to rotatably hold one end of the ball screw 111 with respect to the upper plate 104. In the example shown in FIG. 6 as well, the movable plate 105 is lowered by the mold opening / closing mechanism 109 to bring the movable mold 119 into contact with the fixed mold 120, and then the half nut 118 is engaged with the tie bar to form the mold that is the pressing mechanism 106. The clamping cylinder 107 is operated to clamp the dies 119 and 120. Further, the example in which the mold opening / closing mechanism of the present invention is used for the vertical mold clamping device is not limited to the example of FIG. 6, and various types can be adopted. As an example, the movable plate 105 may be moved up and down by four mold opening and closing mechanisms. Alternatively, a rotatable rotary table may be attached to the lower fixed plate 102 or the movable plate 105, and the dies 119 and 120 attached to the rotary table may move as the table rotates. Further, although the illustration of the injection device is omitted here, various arrangements can be adopted.

In each of the above embodiments, the mold clamping cylinder of the pressure clamping mechanism may be provided on a movable plate. Alternatively, the servomotor of the mold opening / closing mechanism may be attached to the fixed plate, and the ball screw nut may be attached to the movable plate. Further, the servomotor (motor) of the mold opening / closing mechanism may be mounted on the movable plate, and the ball screw nut may be provided on the fixed plate or the bed. The driving force is transmitted from the servo motor (motor) of the mold opening / closing mechanism to the ball screw using a gear (including a speed reducer) between the ball screw and the drive shaft of the motor or a gear (speed reducer). ) And driving force transmission using a belt. Further, a timing belt wound around one driven pulley of a ball screw may be driven by two servomotors (electric motors). The motor may be a motor other than the servo motor. Further, in the present invention, each of the above-described embodiments and their modifications may be combined.

The present invention will not be enumerated one by one, but is not limited to the above-described embodiment, and it is needless to say that the present invention is also applied to those modified by a person skilled in the art based on the gist of the present invention. is there. The molding machine may be an injection molding machine for die casting containing a metal such as magnesium, in addition to an injection molding machine for resin molding. Alternatively, a stamping molding machine for directly supplying a molding material onto a mold may be used. Further, a press molding machine, a vacuum molding machine, a hollow molding machine, a compression molding machine, or the like may be used. In particular, in press molding machines and the like, a vertical type in which a movable platen is moved in a vertical direction is generally used.

11 Injection molding machine
Reference Signs List 12 injection device 13 mold clamping device 21 mold opening / closing mechanism 22 pressure clamping mechanism 27 mold clamping cylinder 33 ball screw nut 38 ball screw 42, 43 driven pulley 44, 45 servo motor (electric motor)
46,47 Driving pulley 48,49 Timing belt

Claims (4)

In a molding machine in which a movable plate on which a movable mold is mounted is moved by a mold opening / closing mechanism with respect to a fixed plate on which a fixed mold is mounted, and press-clamped by a press-clamp mechanism,
The mold opening and closing mechanism includes:
At least two ball screws,
At least two electric motors each driving one ball screw of each ball screw;
A ball screw nut through which each ball screw is inserted,
A molding machine characterized by comprising: A ball screw with two leads of equal pitch,
Two driven pulleys fixed to the ball screw,
Two electric motors respectively driving the ball screws,
A drive pulley fixed to a drive shaft of the electric motor,
One belt stretched over one of the two driven pulleys and a driving pulley of one of the two electric motors;
The other belt pulled over the other driven pulley of the two driven pulleys and the drive pulley of the other motor of the two motors,
A ball screw nut into which the two ball screws are inserted,
The molding machine according to claim 1, further comprising: Four tie bars are inserted through the movable platen,
3. The molding machine according to claim 1, wherein the ball screw nuts are respectively fixed below the circumferential upper end surfaces of the two lower tie bars. A method of controlling a molding machine, in which a movable plate on which a movable mold is mounted is moved by a mold opening / closing mechanism with respect to a fixed plate on which a fixed mold is mounted, and press-clamping is performed by a pressure-clamping mechanism,
The mold opening and closing mechanism includes:
At least two ball screws,
At least two servo motors each driving one ball screw of each ball screw;
A ball screw nut into which each ball screw is inserted,
A method for controlling a molding machine, wherein the position of a movable platen is detected by an encoder of one of the servomotors.